An adhesive tape is used as a reliable adhesive joint member having excellent workability to fix members therebetween, provisionally fix members therebetween, label product information, or the like, in industrial fields such as office automation equipment, IT—home electric appliances, or automobiles. In recent years, the demand for recycling and reusing used products has increased in various industrial fields such as home electrical appliances or automobiles from the standpoint of protection of the earth's environment. In the case where various products are recycled or reused, although adhesive tapes used to fix members or as labels are required to be delaminated therefrom, the adhesive tapes are used on various positions in the products, and therefore a decrease in the operation cost by performing a simple removing process is demanded.
As an easily dismantlable adhesive tape, an adhesive member having at least two adhesive layers, the adhesion forces of which are different from each other, is disclosed, for example (see Patent Document 1). The adhesive tape is an adhesive member which realizes both strong fixation of an adherend and easy dismantling at a weakly-adhesive layer serving as the delamination face by joining the adherend via the weakly-adhesive layer of the adhesive member including adhesive layers with a superposed structure. However, the adhesive member has a problem in that the production cost thereof increases, because plural adhesive agent layers are essential components thereof. In addition, since the structure of the adhesive member allows bonding with an adherend via the weakly-adhesive layer, there is a limitation on an increase in the adhesion force thereof, and it is difficult for the adhesive member to be used to strongly fix members. In particular, there is a case where the adhesive tape is required to exhibit favorable adhesion properties under high temperature, because the adhesive tape is often used under circumstances where heat is applied thereto when the adhesive tape is used to fix members in office automation equipment, IT—home electric appliances, automobiles, or the like.
As another easily dismantlable adhesive composition, an adhesive composition containing an aliphatic polyester is disclosed (see Patent Document 2). The adhesive composition is disclosed to be easily delaminable due to hydrolysis-promoting action of polycaprolactone when immersed in hot water in a delaminating process. However, since the adhesive composition requires to be immersed in hot water when delamination is performed, the equipment cost is high when the adhesive composition is applied to a part having a large size to be dismantled, and the adhesive composition cannot be applied to parts to which water cannot be applied when reused, such as electronic parts.
Even if the adhesion force of an adhesive tape significantly decreases when dismantling is performed, there is a case where removing of a remaining adhesive agent layer is required to delaminate the adhesive tape from an adherend or a substrate, the remaining adhesive agent layer being caused by cohesion failure in the adhesive agent layer occurring when dismantling is performed, and therefore the workability of dismantling a large quantity of industrial products is poor.
An adhesive composition containing a block copolymer obtained by preparing an acrylic copolymer having a carboxyl precursor-group (—COOt-butyl) in an acrylic polymer block and then converting the carboxyl precursor-group to a carboxyl group is disclosed as an adhesive composition using an acrylic block copolymer (see Patent Document 3). Although the adhesive composition is obtained by preparing an acrylic copolymer having a t-butyl group in a side chain thereof as a carboxyl precursor-group, the t-butyl group does not remain in the obtained adhesive composition, and no dismantling properties are exhibited.